From the context of the question, I suspect that the "reflection rule" referred to here is the reflection of the emitter resistance into the base circuitry.

If my assumption is correct then my answer to that question would be that the "reflection rule" is always applied. Bear in mind that there is an intrinsic emitter resistance that is defined by the equation 0.026/Ie. This resistance is usually so small that when a physical emitter resistor is included, the intrinsic emitter resistance can be conveniently ignored.